1. Field of the Invention
The present invention relates generally to semiconductor fabrication methods and, more particularly, to metal fill-in of small contact holes.
2. Description of Related Art
Metal fill-in of contact holes in integrated circuits employing sub-32 nm technology is complicated by the presence of profile irregularities which may form using prior art methods of contact hole formation. Irregularities such as overhang and bowing in contact hole profiles can cause, for example, voids or seams in filled-in metal, thereby reducing the conductance of a contact to be formed through the contact hole. Failure to control such conductance can degrade reliability, reduce yields, and increase manufacturing costs of integrated circuits.
A need thus exists in the prior art for a method to reduce and/or eliminate effects of overhang profiles in integrated circuit contact holes. A further need exists for methods to mitigate effects of bowing.